CN111807808A - A kind of preparation method of high temperature resistant thermal insulation composite material - Google Patents

Abstract

The invention relates to a preparation method of a high-temperature-resistant and heat-insulating composite material, belonging to the technical field of composite material preparation. The purpose of the present invention is to realize the high montmorillonite filling while improving the mechanical properties of the material, the method is as follows: the montmorillonite is placed in a NaCl solution, stirred in an oil bath, removed Cl ^, and dried; add organic The polymer was mixed uniformly, ethyl acetate was added, stirred at room temperature for 30 minutes, and the ethyl acetate was removed to volatilize to obtain organic hybrid montmorillonite; phosphate resin and metal oxide were mixed in a mass ratio of 1:1, and the The phosphate adhesive is extracted, added to the prepared organic hybrid montmorillonite, mixed evenly, put into a mold, and pressed into a cylindrical sample; the molded material can be cured at a stepped temperature. The method is used to prepare an organic-inorganic hybrid montmorillonite composite material which is co-hybridized with a phosphate and a high temperature resistant polymer, so that it has certain strength and deformation ability.

Description

A kind of preparation method of high temperature resistant thermal insulation composite material

technical field

The invention belongs to the technical field of composite material preparation, and in particular relates to a preparation method of a high temperature resistant and heat insulating composite material.

Background technique

In recent years, my country's aerospace industry has achieved rapid development. The friction between the space shuttle and the air will produce aerodynamic heating, which will cause the surface of the aircraft to rapidly rise to a very high temperature. Take the space shuttle as an example. The peak temperatures of the nose cone, the leading edge of the wing, the leeward side and the windward side can reach 1600°C, 1260°C, 500°C and 500-1200°C respectively. Due to the rise in temperature, higher temperature resistance and thermal insulation requirements are put forward for the materials selected for spacecraft. And with the increase of flying height, there are certain requirements for the mechanical properties and compressive ability of the material. Thermal insulation materials can be divided into organic materials and inorganic materials, which have their own advantages and disadvantages. Inorganic thermal insulation materials have the advantages of good fire resistance and flame retardant performance, but they have the disadvantages of large thermal conductivity and slightly poor thermal insulation effect. At present, the most widely used ones in the market are: clay, mineral wool, calcium silicate, etc.; organic thermal insulation materials have low thermal conductivity and good thermal insulation effect, including polyurethane, silicone resin, etc. Its single use is limited, so in order to make the material have more excellent properties, researchers have studied composite materials prepared from organic polymers and inorganic materials.

Montmorillonite (Al, Mg) ₂ (SiO ₁₀ )(OH) ₂ ·n H ₂ O is a naturally occurring layered aluminosilicate mineral with a layered structure mainly composed of tetrahedral (Si-O)-octahedral ( It is composed of a three-layer structure such as Mg-O, Al-O)-tetrahedron (Si-O). The high water absorption capacity of montmorillonite is due to the negative charge on the montmorillonite sheet. In order to play a comprehensive role in the negative charge, there are a large number of metal cations in the montmorillonite sheet. The existence of these metal cations The montmorillonite has strong cation exchange capacity. Montmorillonite has low density, low thermal conductivity, relatively high melting point, some toughness, and is chemically inert, durable, and environmentally safe. As a lightweight porous material, montmorillonite has excellent thermal insulation properties, and its high temperature stability makes it resistant to high temperature differences, thus becoming a thermal insulation layer material in high temperature environments.

Phosphate resin is a large molecular weight inorganic salt resin prepared from phosphoric acid or concentrated phosphoric acid. Phosphate resin and curing agent (commonly used metal oxides, hydroxides, metal salts) will undergo cross-linking reaction at room temperature to form a network Structured phosphate adhesive. Phosphate adhesives have the advantages of high bonding strength, high temperature resistance, stable chemical properties and non-toxicity, and are widely used in many aspects. At present, the application of organic polymer materials is more and more extensive. It is well known that most polymers have the defects of flammability and heat resistance at high temperature. Therefore, research on modification of polymer materials is carried out to realize the high temperature resistance characteristics of polymer materials. Silicone materials and phenolic resin materials are the most widely used high temperature resistant polymer materials. They have good high temperature resistance properties and are widely used.

At present, the application research of montmorillonite in the field of thermal insulation composite materials is divided into two aspects: one is to directly add the treated montmorillonite powder or particles as fillers to the polymer to improve the mechanical properties of the polymer , thermal properties and gas barrier ability, due to insufficient exfoliation and alignment of montmorillonite in the organic polymer matrix, in order to prevent aggregation, the concentration of montmorillonite in the composite material is usually very low, generally not more than 10wt%. The researchers prepared PA-6/MMT nanocomposites by direct melt blending. By simultaneously melt mixing and molding the MMT treated with maleic anhydride and PA-6, the results showed that in the tensile test, with With the increase of MMT content, the tensile modulus and strength of nanocomposites tended to increase, and the tensile strengths were 27.9 MPa, 34.08 MPa, 35.28 MPa when the treated montmorillonite content was 0%, 2%, and 5%, respectively. MPa, but the elongation at break of the material decreases by a cliff while the tensile strength increases, and the addition of montmorillonite has a small increase in the glass transition temperature of the material but the maximum decomposition temperature is almost unchanged. The second is to use montmorillonite as the main material. Due to the low mechanical strength of the montmorillonite material, the polymer is used as a binder and a reinforcing material to exert the excellent properties of the polymer itself. The researchers prepared flexible montmorillonite-polyethylene glycol nanocomposite films by means of ultraviolet light cross-linking. Specifically, the nanoparticles were mixed with polyethylene glycol dimethacrylate and 2-hydroxyl as a photoinitiator. -2-Methylacetophenone mixed in the treated glass plate interlayer was cross-linked and cured under UV light, resulting in a flexible hybrid film. The results showed that the film was filled with 70% montmorillonite. (1cm×1cm×60μm) retained its original morphology under the flame of 120s, and the mechanical properties of the composites were improved due to the addition of montmorillonite, and the montmorillonite composites at 0%, 69%, 74.3% content The tensile strengths of the composites are 0.74MPa, 3.64MPa, and 4.58MPa respectively. It is not difficult to find that the content of montmorillonite plays a key role in the performance of the composite material. The increase of the content of montmorillonite has a good effect on the thermal performance of the composite material. However, the tensile strength of the material is not high and the ability to withstand heat is also very limited, so how to make the material have high mechanical and thermal properties under the condition of high montmorillonite filling is very important.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of a high temperature resistant and heat insulating composite material in order to realize high montmorillonite filling and at the same time improve the mechanical properties of the material.

To achieve the above object, the technical scheme adopted by the present invention is as follows:

A preparation method of a high temperature resistant and heat insulating composite material, the method steps are:

Step 1: Put the montmorillonite in a 1mol/L NaCl solution, under the condition of an oil bath of 80 °C, and treat it at a stirring speed of 2000 rpm for 4 hours. The treated montmorillonite is washed repeatedly with distilled water to remove it. Among them, Cl ^- was dried in an oven at 40°C for 12h;

Step 2: Add organic polymer to the treated montmorillonite material, mix evenly, add ethyl acetate to make the organic polymer and montmorillonite mix more fully, stir at room temperature for 30 minutes, and place in an oven at 40°C During 12h, ethyl acetate was volatilized to obtain organic hybrid montmorillonite;

Step 3: Mix the phosphate resin and the metal oxide in a mass ratio of 1:1, and develop it in a mortar so that it can be fully contacted to prepare a phosphate adhesive;

Step 4: Add the phosphate adhesive to the prepared organic hybrid montmorillonite, stir and mix well, put the uniformly mixed material into the mold, and press it into a cylindrical sample on a pneumatic press at a pressure of 2MPa ;

Step 5: The formed material is cured at a stepped temperature, and cured in an oven at 80°C, 120°C, and 150°C for 30 minutes, and then cured at 180°C for 2 hours.

Compared with the prior art, the present invention has the following beneficial effects: the method is used to prepare an organic-inorganic hybrid montmorillonite composite material which is co-hybridized with a phosphate and a high temperature resistant polymer, so that it has certain strength and deformability. Most of the existing researches are to add a small amount of inorganic rigid particle fillers to the polymer to improve the mechanical and thermal properties of the polymer material. However, since the dispersion of rigid particles in it is difficult to achieve uniform, the amount of rigid particles added is Relatively few, mostly below 10%, lead to the failure to give full play to the excellent performance of inorganic fillers, and few people have studied the effect of toughening of rigid particles. The inorganic filler with high filling content in this experiment can maintain a good morphological structure at a high temperature of 1000 degrees Celsius because of its good refractory type, and has good toughness and can produce certain deformation, thereby improving the impact resistance of the material. performance and mechanical strength.

Description of drawings

Figure 1 shows the compressive deformation capacity diagram of montmorillonite: phosphate at different ratios;

Figure 2 is a graph of the compressive strength of montmorillonite: phosphate at different ratios;

Figure 3 shows the morphology of montmorillonite: phosphate: phenolic resin = 350:100:100 before calcination at 1000°C;

Fig. 4 is a morphology diagram of montmorillonite: phosphate: phenolic resin = 350:100:100 after calcination at 1000°C.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall cover within the scope of the present invention.

Embodiment 1: This embodiment describes a preparation method of a high temperature resistant and heat insulating composite material, and the method steps are:

Step 1: Chemically treat the montmorillonite, put the montmorillonite in a 1 mol/L NaCl solution, and treat it for 4 hours at a stirring speed of 2000 rpm under the condition of an oil bath at 80 °C. Repeated rinsing with distilled water to remove Cl ^- was carried out with AgNO ₃ solution for detection. When Cl ^- disappeared, the treated material was placed in an oven at 40°C for drying for 12 hours; the treatment of montmorillonite with sodium chloride was mainly Due to the high cation exchange capacity of montmorillonite, the entry of sodium ions can expand the interlayer spacing of montmorillonite and even make montmorillonite partially peel off. The small particle size of montmorillonite can make the mixing uniformity of the composite material higher and improve the performance index of the material.

Step 2: Add an organic polymer with good heat resistance to the treated montmorillonite material, mix evenly, and add a certain amount of ethyl acetate that is volatile and will not react with the material to make the organic polymer and montmorillonite. The mixing is more complete, stirring at room temperature for 30 minutes, and placing it in an oven at 40 ° C for 12 hours to volatilize the ethyl acetate to obtain organic hybrid montmorillonite; ethyl acetate is equivalent to the solvent or diluent of the high temperature polymer used. Due to the poor fluidity of the high solid content polymer, in order to make the high temperature resistant polymer material fully contact and mix with the treated montmorillonite, the high temperature resistant polymer material is diluted to make the mixing more uniform. The effect of adding high temperature resistant polymer is first to have certain adhesive properties, and due to the high viscosity, the layered montmorillonite material can be further peeled off in the process of mixing with montmorillonite, and secondly, the selected high temperature resistant polymer The material has a lower thermal conductivity, and has a higher residual carbon content to play a better role in the thermal insulation performance of the material.

Step 3: Mix the phosphate resin and the metal oxide in a mass ratio of 1:1, and develop the mixture in a mortar so that the mixture of the phosphate resin and the metal oxide can be fully contacted and mixed to prepare a phosphate adhesive;

Step 4: Add the phosphate adhesive to the prepared organic hybrid montmorillonite, stir and mix well, put the uniformly mixed material into the mold, and press it on a pneumatic press with a pressure of 2MPa to a diameter d= 1.3cm, cylindrical sample with a height of 1.0cm;

Step 5: The formed material is cured at a stepped temperature, and cured in an oven at 80°C, 120°C, and 150°C for 30 minutes, and then cured at 180°C for 2 hours. Since the high temperature-resistant organic polymer will form a porous structure of bubbles during the heating process, in order to reduce the amount of bubbles, the number of open pores, and the size of the pores and bubbles, it is necessary to carry out a curing reaction and use a slow heating operation.

Embodiment 2: In the method for preparing a high temperature resistant and heat insulating composite material according to Embodiment 1, in step 1, the ratio of the montmorillonite to the NaCl solution is 10g:100mL.

Embodiment 3: In the method for preparing a high temperature resistant and heat insulating composite material according to Embodiment 1, in step 2, the organic polymer will be cured at a temperature above 80°C, and after curing, a cross-linked network structure will appear. , and the ablated polymer produces carbon. The cross-linked network structure can make it have excellent bonding performance, with high bonding strength, the strength can reach 10-20MPa, and this organic polymer after ablation will generate a large amount of carbon, carbon has good The heat insulation and flame retardant effect of this kind of high temperature resistant polymer material have obtained high application value in the field of high temperature resistant heat insulation and flame retardant.

Embodiment 4: In the method for preparing a high temperature resistant and heat insulating composite material according to Embodiment 1, in step 3, the metal oxide is a mixture of Al ₂ O ₃ , ZnO and MgO. This mixture of metal oxides is a hardener product mixed in a certain proportion.

Embodiment 5: The method for preparing a high temperature resistant and heat insulating composite material according to Embodiment 1, montmorillonite: phosphate adhesive: organic polymer = 100-450: 100:50 or montmorillonite: phosphate Adhesive: organic polymer=100～450:100:100.

Example 1:

The compressive strength and deformation ability of the prepared composite samples were tested by a universal testing machine, as shown in Figures 1 and 2. The experimental results are that phosphate: montmorillonite = 100 without adding high temperature organic polymers : 250, compressive strength 33.96MPa, deformation 12%; Phosphate: montmorillonite = 100:300, compressive strength 36.92MPa, deformation 11.67%; Phosphate: montmorillonite = 100:350 sample, resistance The compressive strength reaches 42.67MPa, and the deformation can reach 11%; phosphate: montmorillonite = 100:400, the compressive strength is 38.14MPa, and the deformation is 10%; phosphate: montmorillonite = 100:450, the compressive strength is 36.22MPa , the deformation is 10.67%. After adding organic polymer, according to phosphate: montmorillonite: organic polymer = 100: (100-450): 50, the compressive strengths are 16.32MPa, 17.53MPa, 20.46MPa, 26.21MPa, 26.45MPa, 35.67MPa, respectively , 38.34MPa, 32.22MPa, the deformation is 8%, 12.67%, 13.67%, 10.7%, 13.33%, 13%, 14.7%, 14.7%, respectively. Further increase the content of high temperature resistant organic polymer and mix it according to the ratio of phosphate: montmorillonite: organic polymer = 100: (100-450): 100, the compressive strengths are 7.22MPa, 14.515MPa, 14.813MPa, 17.49 MPa, 20.43MPa, 24.95MPa, 27.84MPa, 28.65MPa, the deformation is 5.33%, 9%, 11%, 10.67%, 11.67%, 13.67%, 15.67%, 17%, respectively. According to the above data, it can be found that the compressive strength first increases and then decreases with the increase of montmorillonite content, and the compressive strength decreases slightly with the increase of high temperature resistant organic polymer content. , but adding 100 parts of organic polymer, the strain in the sample has been greatly improved.

The cured sample was heated to 1000°C for 10min at 10°C/min in a muffle furnace, and the morphology of the sample was intact and did not change, as shown in Figures 3 and 4, showing excellent high temperature resistance. And in the previous research, it was not found that the composite material prepared with such a high filling amount of montmorillonite had good mechanical properties under the condition of high temperature resistance, and the prepared composite material had a good application prospect.

Claims (5)

1. A preparation method of a high-temperature-resistant heat-insulation composite material is characterized by comprising the following steps: the method comprises the following steps:

the method comprises the following steps: placing montmorillonite in 1mol/L NaCl solution, treating at 80 deg.C in oil bath at stirring speed of 2000rpm for 4 hr, repeatedly washing the montmorillonite with distilled water for several times to remove Cl^-Drying in a 40 ℃ oven for 12 h;

step two: adding an organic polymer into the treated montmorillonite material, uniformly mixing, adding ethyl acetate to ensure that the organic polymer and the montmorillonite are more fully mixed, stirring for 30min at normal temperature, and putting the mixture in a drying oven at 40 ℃ for 12h to volatilize the ethyl acetate to obtain organic hybrid montmorillonite;

step three: mixing a phosphate resin and a metal oxide according to a ratio of 1: 1, grinding in a mortar to enable the mixture of the phosphate resin and the metal oxide to be fully contacted and mixed to prepare the phosphate adhesive;

step four: adding the prepared phosphate adhesive into the prepared organic hybrid montmorillonite, fully stirring and uniformly mixing, putting the uniformly mixed material into a die, and pressing the material into a cylindrical sample on a pneumatic press under the pressure of 2 MPa;

step five: curing the formed material at a step-shaped temperature for 30min in an oven at 80 ℃, 120 ℃ and 150 ℃ respectively, and then curing for 2h at 180 ℃.

2. The preparation method of the high-temperature-resistant heat-insulating composite material according to claim 1, characterized by comprising the following steps: in the first step, the ratio of the montmorillonite to the NaCl solution is 10 g: 100 mL.

3. The preparation method of the high-temperature-resistant heat-insulating composite material according to claim 1, characterized by comprising the following steps: in the second step, the organic polymer is cured at a temperature of more than 80 ℃, a crosslinked network structure is formed after curing, and carbon is generated in the ablated polymer.

4. The preparation method of the high-temperature-resistant heat-insulating composite material according to claim 1, characterized by comprising the following steps: in the third step, the metal oxide is Al₂O₃ZnO and MgO.

5. The preparation method of the high-temperature-resistant heat-insulating composite material according to claim 1, characterized by comprising the following steps: montmorillonite: phosphate adhesive: 100-450% of an organic polymer: 100: 50 or montmorillonite: phosphate adhesive: 100-450% of an organic polymer: 100: 100.

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